Don't get me wrong, as I have & do use ECP and their discount codes when it works out at the best price, but have you noticed how frequently they artificially manufacture these savings by ramping up the prices at the same time as giving out discount codes.
For example...their front brake discs for a Z4M (which they regularly sell for about £165), have gone up to £270 - which comes back down to about £165 when you take into account their 'weekend discount code', same goes for their oil...which was about £41 without a discount code.
The average punter seems to think buying a £200 item with a 50% discount is better than buying the same item for £100.
That Castrol Edge is £42 from their sister website CarParts4Less.
So if you want cheap prices all the time, without having to hunt though the whole ECP catalogue to see what actually is a bargain, then just use
CarParts4Less.